Apex domains cannot have CNAME records.
Question and response
Question
dig ferenz.com.br. NS
Answer
ferenz.com.br. 2 NS kia.ns.cloudflare.com.
ferenz.com.br. 2 NS buck.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
kia.ns.cloudflare.com. 3 A 108.162.192.179
kia.ns.cloudflare.com. 3 A 172.64.32.179
kia.ns.cloudflare.com. 3 A 173.245.58.179
buck.ns.cloudflare.com. 3 A 108.162.193.78
buck.ns.cloudflare.com. 3 A 172.64.33.78
buck.ns.cloudflare.com. 3 A 173.245.59.78
kia.ns.cloudflare.com. 3 AAAA 2606:4700:50:0:0:0:adf5:3ab3
kia.ns.cloudflare.com. 3 AAAA 2803:f800:50:0:0:0:6ca2:c0b3
kia.ns.cloudflare.com. 3 AAAA 2a06:98c1:50:0:0:0:ac40:20b3
buck.ns.cloudflare.com. 3 AAAA 2606:4700:58:0:0:0:adf5:3b4e
buck.ns.cloudflare.com. 3 AAAA 2803:f800:50:0:0:0:6ca2:c14e
buck.ns.cloudflare.com. 3 AAAA 2a06:98c1:50:0:0:0:ac40:214e
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0